History - The U.S. Marshals during World War I:

Protection of the Home Front

When President Woodrow Wilson issued the declaration of war against
Germany April 6, 1917, he told the American people that "the supreme
test of the nation has come. We must all speak, act, and serve
together." While American troops fought in the trenches of Europe,
United States Marshals protected the home front against enemy aliens,
spies, saboteurs, and slackers. From the declaration of war on April 6,
1917 to the Armistice on November 11, 1918, U.S. Marshals:

INVESTIGATED 222,768 violations of the selective service laws;

REGISTERED 480,000 German enemy aliens;

ISSUED 200,000 permits to enemy aliens;

ARRESTED 6,300 enemy aliens under Presidential Arrest Warrants;

INTERVIEWED 2,300 enemy aliens in military camps;
and

GUARDED restricted areas around docks, ammunitions factories,
military camps, and other sensitive areas.

On April 2, 1917, President Woodrow Wilson asked
Congress for a declaration of war against Germany. Congress
declared war on April 6, 1917.

Duties of the U.S. Marshals during World War I:

March 27, 1917

Cooperate with local police; take precautions against
hostile acts.

April 6, 1917

War declared. Warn Germans to "Obey the law".

April 10, 1917

Advise Germans to surrender all weapons. explosives, and
radios; arrest any who do not.

April 16, 1917

Arrest specified enemy aliens and turn them over to War
Department for internment.